1. Field of the Invention
The present invention relates generally to sunglasses and more particularly, to a sunglasses device especially adapted for adding on to conventional eyeglasses.
2. Description of the Prior Art
People who wear prescription eyeglasses often have the need for sunglasses. When such is the case, a number of alternative courses of action may be taken. The person may have a pair of prescription sunglasses made. Such is an expensive undertaking. Moreover, it may prove inconvenient to carry around and take very good care of prescription sunglasses.
Another alternative is to use an auxiliary pair of sunglasses. The auxiliary sunglasses have means to attach the sunglasses to the prescription eyeglasses. The auxiliary sunglasses are not made to a prescription and do not have highly refined optical properties such as are present in prescription eyeglasses. The auxiliary sunglasses merely have sun screening properties. The auxiliary sunglasses are generally made from inexpensive plastic materials. The auxiliary sunglasses do not have temple portions and do not fit over the ears of the wearer. For these reasons, the auxiliary sunglasses are relatively inexpensive compared to the prescription eyeglasses. The auxiliary sunglasses attach to either the lens portion or the frame portion of the prescription eyeglasses. They, in essence, ride piggy back on the prescription eyeglasses.
Throughout the years, a number of innovations have been developed relating to auxiliary sunglasses that are carried piggy back by conventional eyeglasses. Many of the innovations are directed to the specific means for attaching the auxiliary sunglasses to the prescription eyeglasses. The following U.S. patents are representative of some of those innovations: U.S. Pat. Nos. 3,876,295; 3,901,589; 4,163,607; 4,247,178; and Des. 274,181.
More specifically, U.S. Pat. Nos. 3,876,295, 4,463,607, and Des. 274,181 disclose auxiliary sunglasses that clip on to lenses of conventional eyeglasses. In each patent, the clip-on mechanism exerts pressure on the lenses of the eyeglasses. As such, the eyeglass lenses can be scratched. This is especially so if a particle of dirt gets sandwiched between the clip-on device and the lenses of the eyeglasses. In this respect, it would be desirable if an auxiliary sunglasses device were provided which rides piggy back on eyeglasses without being supported by the lenses of the eyeglasses.
There is another problem associated with the use of auxiliary sunglasses that clip on to lenses of conventional eyeglasses, such as disclosed in U.S. Pat. Nos. 3,876,295, 4,463,607, and Des. 274,181. By clipping on to the lenses, the clip-on mechanism of the auxiliary sunglasses act as an obstruction to good vision. The clip-on mechanisms occupy some of the lens area and deprive the wearer of a full field of vision. In this respect, it would be desirable if an auxiliary sunglasses device were provided that rode piggy back on conventional eyeglasses without obstruction vision through the lenses of the eyeglasses.
U.S. Pat. No. 3,901,589 discloses clip-on, flip-up goggles that ride piggy back on conventional eyeglasses. In this device, a rigid auxiliary, two-lens goggles structure is provided. The right and left lenses of the goggles structure are not laterally adjustable with respect to each other. The rigid, two-lens, non-laterally-adjustable goggle structure is, however, supported by a laterally adjustable support structure. The laterally adjustable support structure includes spring-biased clamping members which clamp onto the far sides of the frame of the conventional eyeglasses. Because a non-laterally adjustable auxiliary lens structure is supported by a laterally adjustable support structure, an interface assembly must be provided between the two units. The interface unit makes the overall structure quite complex. On the other hand, if a two-lens auxiliary sunglasses device were provided that both laterally adjustable lenses and laterally adjustable support structures, then such a complex interface unit would not be necessary. In this respect, it would be desirable if an auxiliary sunglasses device were provided which includes two laterally adjustable lenses supported by a laterally adjustable lens support.
U.S. Pat. No. 4,247,178 discloses clip-on sunglasses that are supported by a bridge member of the frame of the eyeglasses. This clip-on device includes two auxiliary sunglasses lenses that are rigidly connected to each other and are not laterally adjustable. Moreover, the connection between the auxiliary sunglasses and the eyeglasses is centrally located with respect to both the auxiliary sunglasses and the eyeglasses. The central location of the attachment makes the attachment highly susceptible to destabilizing forces at the edges of the auxiliary sunglasses. A destabilizing force such as a simple bump against an edge of the auxiliary sunglasses can readily knock the auxiliary sunglasses out of alignment with the eyeglasses. In this respect, it would be desirable if an auxiliary sunglasses device were provided which is not readily susceptible to destabilization by light forces applied to the edges of the auxiliary sunglasses.
There are additional features that would be desirable in an auxiliary sunglasses device. Even though a clamping force may be exerted by an auxiliary sunglasses device laterally on the edges of a conventional pair of eyeglasses, it may be desirable if some means were used to increase frictional contact between the auxiliary sunglasses and the conventional eyeglasses so as to provide a more secure attachment between the two. In this respect, it would be desirable if an auxiliary sunglasses device were provided which had means to increase frictional contact between the auxiliary sunglasses and the edges of the conventional eyeglasses.
Lenses and frames of conventional eyeglasses vary considerably in thickness from one pair to another. If an auxiliary sunglasses is designed to fit onto relatively thin lenses and frames, then it may not be suitable for attachment to thicker lenses and frames. On the other hand, if the auxiliary sunglasses are designed to fit onto relatively thick lenses and frames, then, if the auxiliary sunglasses would be used with thinner lenses and frames, the auxiliary sunglasses may be loose and rattle around on the thinner lenses and frames. In this respect, it would be desirable if an auxiliary sunglasses device were provided which were adjustable for a range of thicknesses of eyeglass lenses and frames so that the auxiliary sunglasses engage in a snug fit for each thickness within the adjustable range.
Thus, while the foregoing body of prior art indicates it to be well known to use clip-on sunglasses for conventional eyeglasses, the prior art described above does not teach or suggest a snap-on sunglasses apparatus which has the following combination of desirable features: (1) rides piggy back on eyeglasses without being supported by the lenses of the eyeglasses; (2) rides piggy back on conventional eyeglasses without obstructing vision through the lenses of the eyeglasses; (3) includes two laterally adjustable lenses supported by a laterally adjustable lens support; (4) is not readily susceptible to destabilization by light forces applied to the edges of the auxiliary sunglasses; (5) has means to increase frictional contact between the auxiliary sunglasses and the edges of the conventional eyeglasses; and (6) is adjustable for a range of thicknesses of eyeglass lenses and frames so that the auxiliary sunglasses engage in a snug fit for each thickness within the adjustable range. The foregoing desired characteristics are provided by the unique snap-on sunglasses of the present invention as will be made apparent from the following description thereof. Other advantages of the present invention over the prior art also will be rendered evident.